Aluminum casting alloy

ABSTRACT

An Al casting alloy contains at least five of the following alloying components: Si: 6.0 to 8.5 wt %; Mg: 0.3 to 0.8 wt %; Cr: 0.05 to 0.35 wt %; Fe: 0.05 to 0.25 wt %; Mn: 0.1 to 0.8 wt %; Cu: 0.05 to 0.50 wt %; Sr: 0.005 to 0.030 wt %; Zr≤0.15 wt %; Zn: ≤0.15 wt %; admixtures (total): &lt;0.2 wt %; in each case made up to 100 wt % with Al.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. § 119 of German Application No. 10 2017 127 073.6 filed Nov. 17, 2017, the disclosure of which is incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to an aluminum (Al) casting alloy.

2. Description of the Related Art

Various Al casting alloys are known from DE 10 2008 055 928 A1, DE 10 2012 108 590 A, DE 10 2013 108 127 A1, DE 10 2014 101 317 A1 and DE 10 2015 111 020 A1.

SUMMARY OF THE INVENTION

Starting from this prior art, the task underlying the invention is to provide an improved Al casting alloy, especially a high-strength pressure die-cast alloy, that has an improved castability.

These and other objects are accomplished by an Al casting alloy having the features according to the invention. Further developments and advantageous configurations of the invention are discussed below.

The Al casting alloy according to the invention contains at least five of the following alloying components:

-   Si: 6.0 to 8.5 wt % -   Mg: 0.3 to 0.8 wt % -   Cr: 0.05 to 0.35 wt % -   Fe: 0.05 to 0.25 wt % -   Mn: 0.1 to 0.8 wt % -   Cu: 0.05 to 0.50 wt % -   Sr: 0.005 to 0.030 wt % -   Zr≤0.15 wt % -   Zn: ≤0.15 wt % -   Admixtures (total): <0.2 wt %     in each case made up to 100 wt % with Al.

The selection, according to the invention, of alloying components in the said order of magnitude leads to a significant improvement of the castability and of the mechanical properties. This improvement can be noted already in the as-cast condition, but especially in a cast component after a 2-stage heat treatment, namely a solution annealing and a subsequent aging, wherein preferably a quenching of the cast component in water is provided between these two heat-treatment stages. For chassis applications, preferably for wheel-controlling components, quite preferably for shock absorber struts, wheel mounts and especially pivot bearings, but also for pitman arms or transverse beams, especially integral subframes, mechanical characteristics improved on the whole are obtained in this way.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if, for another area of application, Si is present in a content of at least or of more than 6.0 wt %, preferably of at least or of more than 6.3 wt %, particularly preferably of at least or of more than 6.5 wt %, quite particularly preferably of at least or of more than 6.7 wt %, even more preferably of at least or of more than 6.9 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if, for another area of application, Si is present in a content of at most or of less than 8.5 wt %, preferably of at most or of less than 8.0 wt %, particularly preferably of at most or of less than 7.7 wt %, quite particularly preferably of at most or of less than 7.5 wt %, even more preferably of at most or of less than 7.4 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Mg is present in a content of at least or of more than 0.3 wt %, preferably of at least or of more than 0.35 wt %, particularly preferably of at least or of more than 0.4 wt %, quite particularly preferably of at least or of more than 0.45 wt %, even more preferably of at least or of more than 0.5 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Mg is present in a content of at most or of less than 0.8 wt %, preferably of at most or of less than 0.75 wt %, particularly preferably of at most or of less than 0.7 wt %, quite particularly preferably of at most or of less than 0.65 wt %, even more preferably of at most or of less than 0.60 wt %, even more preferably of at most or of less than 0.55 wt %, even more preferably of at most or of less than 0.50 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Mn is present in a content of at least or of more than 0.2 wt %, preferably of at least or of more than 0.25 wt %, particularly preferably of at least or of more than 0.35 wt %, quite particularly preferably of at least or of more than 0.4 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Mn is present in a content of at most or of less than 0.8 wt %, preferably of at most or of less than 0.75 wt %, particularly preferably of at most or of less than 0.7 wt %, quite particularly preferably of at most or of less than 0.65 wt %, even more preferably of at most or of less than 0.60 wt %, even more preferably of at most or of less than 0.55 wt %, even more preferably of at most or of less than 0.50 wt %, even more preferably of at most or of less than 0.45 wt %, even more preferably of at most or of less than 0.40 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Cr is present in a content of at least or of more than 0.05 wt %, preferably of at least or of more than 0.07 wt %, particularly preferably of at least or of more than 0.09 wt %, quite particularly preferably of at least or of more than 0.10 wt %, even more preferably of at least or of more than 0.11 wt %, even more preferably of at least or of more than 0.12 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Cr is present in a content of at most or of less than 0.20 wt %, preferably of at most or of less than 0.17 wt %, particularly preferably of at most or of less than 0.16 wt %, quite particularly preferably of at most or of less than 0.15 wt %, even more preferably of at most or of less than 0.14 wt %, even more preferably of at most or of less than 0.13 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Fe is present in a content of at least or of more than 0.05 wt %, preferably of at least or of more than 0.07 wt %, particularly preferably of at least or of more than 0.08 wt %, quite particularly preferably of at least or of more than 0.09 wt %, even more preferably of at least or of more than 0.10 wt %, even more preferably of at least or of more than 0.11 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Fe is present in a content of at most or of less than 0.25 wt %, preferably of at most or of less than 0.22 wt %, particularly preferably of at most or of less than 0.19 wt %, quite particularly preferably of at most or of less than 0.17 wt %, even more preferably of at most or of less than 0.15 wt %, even more preferably of at most or of less than 0.13 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Cu is present in a content of at least or of more than 0.05 wt %, preferably of at least or of more than 0.10 wt %, particularly preferably of at least or of more than 0.15 wt %, quite particularly preferably of at least or of more than 0.20 wt %, even more preferably of at least or of more than 0.25 wt %, even more preferably of at least or of more than 0.30 wt %, even more preferably of at least or of more than 0.35 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Cu is present in a content of at most or of less than 0.50 wt %, preferably of at most or of less than 0.45 wt %, particularly preferably of at most or of less than 0.40 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Sr is present in a content of at least or of more than 0.005 wt %, preferably of at least or of more than 0.007 wt %, particularly preferably of at least or of more than 0.009 wt %, quite particularly preferably of at least or of more than 0.011 wt %, even more preferably of at least or of more than 0.013 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Sr is present in a content of at most or of less than 0.030 wt %, preferably of at most or of less than 0.025 wt %, particularly preferably of at most or of less than 0.022 wt %, quite particularly preferably of at most or of less than 0.020 wt %, even more preferably of at most or of less than 0.018 wt %.

The Al casting alloy according to the invention may contain admixtures, for example manufacturing-related impurities such as Pb, Ni, etc. These may be desired admixtures, which increase the strength of the Al casting alloy or of components cast from it, without negatively affecting the castability of the Al casting alloy.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if admixtures are present on the whole in a content of at most or of less than 0.2 wt %, preferably of at most or of less than 0.18 wt %, particularly preferably of at most or of less than 0.16 wt %, quite particularly preferably of at most or of less than 0.14 wt %, even more preferably of at most or of less than 0.12 wt %, even more preferably of at most or of less than 0.10 wt %, even more preferably of at most or of less than 0.08 wt %, even more preferably of at most or of less than 0.06 wt %, even more preferably of at most or of less than 0.04 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if other admixtures are present on the whole in a content of at least or of more than 0.01 wt %, preferably of at least or of more than 0.03 wt %, particularly preferably of at least or of more than 0.05 wt %, quite particularly preferably of at least or of more than 0.07 wt %, even more preferably of at least or of more than 0.09 wt %, even more preferably of at least or of more than 0.11 wt %, even more preferably of at least or of more than 0.13 wt %, even more preferably of at least or of more than 0.15 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Zr is present in a content of at most or of less than 0.05 wt %, preferably of at most or of less than 0.025 wt %, particularly preferably of at most or of less than 0.01 wt %, quite particularly preferably of at most or of less than 0.005 wt %, even more preferably of at most or of less than 0.003 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Zr is present in a content of at least or of more than 0.001 wt %, preferably of at least or of more than 0.002 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Zn is present in a content of at least or of more than 0.001 wt %, preferably of at least or of more than 0.003 wt %, particularly preferably of at least or of more than 0.005 wt %, quite particularly preferably of at least or of more than 0.010 wt %.

For an optimization of the castability and/or of the mechanical characteristics, it may be advantageous if Zn is present in a content of at most or of less than 0.15 wt %, preferably of at most or of less than 0.075 wt %, particularly preferably of at most or of less than 0.05 wt %, quite particularly preferably of at most or of less than 0.025 wt %, even more preferably of at most or of less than 0.020 wt %, even more preferably of at most or of less than 0.015 wt %.

It may be advantageous if the Al casting alloy is a pressure die-casting alloy.

It may be advantageous if the Al casting alloy is a vacuum die-casting alloy.

Correspondingly, the invention also relates to a method for the manufacture of a cast component from an Al casting alloy according to the invention, in which the pressure, preferably the vacuum die-casting process, such as is described in DE 10 2010 046 041 A1, for example, finds application.

It may be advantageous if the components cast from the Al casting alloy according to the invention are subjected to a two-stage heat treatment, namely a solution annealing and a subsequent artificial aging. It may be advantageous if the cast component is quenched in water between the two heat-treatment stages.

It may be advantageous if the cast component, after the casting process, is solution-annealed between 480° C. and 540° C., preferably between 490° C. and 520° C., particularly preferably between 500° C. and 515° C. for 10 to 60 minutes, preferably for 15 to 40 minutes, particularly preferably for 20 to 40 minutes.

It may be advantageous if the cast component, after the casting process and the solution-annealing, is tempered between 130° C. and 220° C., preferably between 140° C. and 200° C., particularly preferably between 160° C. and 180° C., for 4 to 8 hours, preferably for 5 to 7 hours, particularly preferably for 5.5 to 6.5 hours.

It may be advantageous if the tempering takes place in two steps, namely in a first step between 130° C. and 150° C. for 4 to 6 hours and a subsequent second step between 170° C. and 200° C. for 1 to 5 hours.

The invention further provides the use of the Al casting alloy according to the invention or a cast component, especially heat-treated, from the Al casting alloy according to the invention for chassis parts of motor vehicles, especially for transverse beams or integral subframes or for wheel-controlling components of motor vehicles, quite particularly preferably for shock absorber struts, wheel mounts or pivot bearings of motor vehicles.

The very good castability of the Al casting alloy according to the invention permits the manufacture of a casting free of shrinkage holes.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Cast components that are manufactured from an Al casting alloy according to the invention are characterized after a two-stage treatment by an offset yield strength RP0.2 of ≥290 MPa, preferably of 290 to 320 MPa, and/or an elongation at break A5 of >6%, preferably of 7 to 10%.

EXAMPLE

1. For determination of the mechanical properties of an AlSi7MgMnCrCu alloy according to the invention that contains 6.99 wt % Si, 0.44 wt % Mg, 0.12 wt % Cr, 0.11 wt % Fe, 0.30 wt % Mn, 0.11 wt % Ti, 0.26 wt % Cu, 0.017 wt % Sr, 0.008 wt % Zn, 0.008 wt % Ca and impurities of less than 0.1 wt %, in each case made up to 100 wt % with Al, tension bars according to DIN 50125 were cut out from a component manufactured by means of a vacuum die-casting process, especially from a strut tower, wherein the component had been subjected beforehand to a heat treatment (a) solution annealing at 510° C. for 30 minutes, quenching in water, artificial aging at 180° C. for 7.5 hours; b) solution annealing at 510° C. for 30 minutes, quenching in water, artificial aging at 170° C. for 6 hours).

2. For determination of the mechanical properties of an AlSi7MgMnCrCu alloy according to the invention that contains 7.30 wt % Si, 0.54 wt % Mg, 0.12 wt % Cr, 0.12 wt % Fe, 0.40 wt % Mn, 0.12 wt % Ti, 0.38 wt % Cu, 0.014 wt % Sr, 0.013 wt % Zn, 0.006 wt % Ca and impurities of less than 0.1 wt %, in each case made up to 100 wt % with Al, tension bars according to DIN 50125 were cut out from a component manufactured by means of a vacuum die-casting process, especially from a strut tower, wherein the component had been subjected beforehand to a heat treatment (a) solution annealing at 510° C. for 30 minutes, quenching in water, artificial aging at 170° C. for 8 hours; b) solution annealing at 510° C. for 30 minutes, quenching in water, artificial aging at 140° C. for 5 hours and 180° C. for 2 hours).

The casting of comparison components takes place under the same conditions. The alloys to be compared differ as indicated above. Each specimen bar is taken at the same place of the component, in the present case the strut tower. The mechanical properties of offset yield strength Rp0.2, elongation at break A5 and tensile strength Rm according to DIN10002 are determined.

Rp 0.2 A5 Rm [Mpa] [%] [Mpa] 1.a) AlSi7MgMnCrCu 290  7-10 350 1.b) AlSi7MgMnCrCu 300 6-8 365 2.a) AlSi7MgMnCrCu 320 6-9 380 2.b) AlSi7MgMnCrCu 305 7-9 370

Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention. 

1. An aluminum casting alloy, which contains at least five of the following alloying components: Si: 6.0 to 8.5 wt % Mg: 0.3 to 0.8 wt % Cr: 0.05 to 0.35 wt % Fe: 0.05 to 0.25 wt % Mn: 0.1 to 0.8 wt % Cu: 0.05 to 0.50 wt % Sr: 0.005 to 0.030 wt % Zr≤0.15 wt % Zn: ≤0.15 wt % Admixtures (total): <0.2 wt % in each case made up to 100 wt % with Al.
 2. The aluminum casting alloy according to claim 1, wherein Si is present in a content of at least 6.3 wt %.
 3. The aluminum casting alloy according to claim 1, wherein Si is present in a content of at most 8.0 wt %.
 4. The aluminum casting alloy according to claim 1, wherein Mg is present in a content of at least 0.35 wt %.
 5. The aluminum casting alloy according to claim 1, wherein Mg is present in a content of at most 0.75 wt %.
 6. The aluminum casting alloy according to claim 1, wherein Mn is present in a content of at least 0.2 wt %.
 7. The aluminum casting alloy according to claim 1, wherein Mn is present in a content of at most 0.75 wt %.
 8. The aluminum casting alloy according to claim 1, wherein Cr is present in a content of at least 0.07 wt %.
 9. The aluminum casting alloy according to claim 1, wherein Cr is present in a content of at most 0.20 wt %.
 10. The aluminum casting alloy according to claim 1, wherein Fe is present in a content of at least 0.07 wt %.
 11. The aluminum casting alloy according to claim 1, wherein Fe is present in a content of at most 0.22 wt %.
 12. The aluminum casting alloy according to claim 1, wherein Cu is present in a content of at least 0.10 wt %.
 13. The aluminum casting alloy according to claim 1, wherein Cu is present in a content of at most 0.45 wt %.
 14. The aluminum casting alloy according to claim 1, wherein Sr is present in a content of at least 0.007 wt %.
 15. The aluminum casting alloy according to claim 1, wherein Sr is present in a content of at most 0.025 wt %.
 16. The aluminum casting alloy according to claim 1, wherein the admixtures are present in total in a content of at most 0.18 wt %.
 17. The aluminum casting alloy according to claim 1, further comprising other admixtures present in total in a content of at least 0.01 wt %.
 18. The aluminum casting alloy according to claim 1, wherein Zr is present in a content of at most 0.05 wt %.
 19. The aluminum casting alloy according to claim 1, wherein Zr is present in a content of at least 0.001 wt %.
 20. The aluminum casting alloy according to claim 1, wherein Zn is present in a content of at least 0.001 wt %. 21-23. (canceled) 